National Natural Science Foundation of China(41977037)；Natural Science Foundation of Jiangsu Province(BK20190092)；Innovation and Entrepreneurship Training program for College students in Jiangsu Province(202110300110Y)
亚硝酸盐型甲烷厌氧氧化（nitrite-dependent anaerobic methane oxidation，n-damo）是控制稻田甲烷排放的一种新途径，但有关其对大气CO2升高的响应尚不清楚。依托开顶式气室组成的CO2浓度自动调控平台，设置环境CO2浓度处理（CK）和CO2缓增处理（EC：每年增加40 μL·L-1，至采样时CO2浓度为CK+160 μL·L-1）。采用稳定性同位素示踪、定量PCR和高通量测序等手段，分析不同CO2处理下水稻关键生育期（分蘖期、拔节期和开花期）稻田n-damo活性及其功能微生物Candidatus Methylomirabilis oxyfera（M. oxyfera）-like细菌的丰度、多样性和群落组成。结果发现，供试土壤中n-damo活性为CO2 0.31～5.09 nmol g-1·d-1，M. oxyfera-like细菌丰度为7.51×106～5.49×107copies·g-1。CO2缓增一定程度上刺激了土壤中n-damo活性以及M. oxyfera-like细菌丰度，且在拔节期达到显著性水平：活性和丰度分别增加了137.9%和96.0%。同时还使M. oxyfera-like细菌的群落组成发生显著改变，并影响其多样性。EC处理下土壤可溶性有机碳含量和无机氮含量的改变很可能是导致n-damo活性及M. oxyfera-like细菌群落结构发生变化的重要原因。综上，稻田n-damo过程对大气CO2浓度缓增具有正响应。
【Objective】The process of nitrite-dependent anaerobic methane oxidation (n-damo) catalyzed by Candidatus Methylomirabilis oxyfera (M. oxyfera) -like bacteria links both the carbon and nitrogen cycles, and has attracted great attention in recent years because of its potential role acting as a microbial methane sink. This process has been reported to be a novel pathway for controlling methane emissions from paddy ecosystems. Elevated atmospheric CO2 concentration can indirectly affect the structure and function of soil microbial communities. However, the response of n-damo to e[CO2] is poorly known. This study aims to explore the response of n-damo activity, and the community composition and abundance of M. oxyfera-like bacteria to e[CO2] in a paddy ecosystem.【Method】Here, ambient CO2 treatment (CK) and a slow increase of atmospheric CO2 treatment (EC: an increase of 40 μL·L-1 per year above CK until 160 μL·L-1) were set up based on the CO2 automatic control platform with open-top chambers. The stable isotope tracer experiment, quantitative PCR and high-throughput sequencing were employed to investigate the n-damo activity, abundance, diversity and community composition of M. oxyfera-like bacteria in paddy soils across three key rice growth stages (tillering, jointing and flowering stages) under different CO2 treatments.【Result】The results showed the occurrence of n-damo activity and the presence of M. oxyfera-like bacteria in the studied paddy soils. It was found that the n-damo activity ranged from 0.31 to 5.09 nmol CO2 g-1·d-1, and the abundance of M. oxyfera-like bacteria varied between 7.51×106 and 5.49×107copies g-1. Furthermore, EC treatment stimulated the n-damo activity and abundance of M. oxyfera-like bacteria, particularly at the jointing stage, in which the activity and abundance were increased by 137.9% and 96.0%, respectively. In addition, EC treatment significantly changed the community composition and diversity of M. oxyfera-like bacteria, and the diversity was increased under EC treatment. Correlation analyses showed that the soil dissolved organic carbon content, ammonium content, nitrate content and water content all had significant impacts on the community structure of M. oxyfera-like bacteria. The variations in soil dissolved organic carbon content and inorganic nitrogen content under EC treatment could probably cause the change of n-damo activity and the abundance of M. oxyfera-like bacteria.【Conclusion】Elevated atmospheric CO2 promoted the n-damo activity and M. oxyfera-like bacterial abundance and significantly changed the community structure of M. oxyfera-like bacteria in a paddy ecosystem. In addition, the changes of soil dissolved organic carbon content, inorganic nitrogen content and water content greatly affected the n-damo activity and community structure of M. oxyfera-like bacteria. Taken together, our results showed a positive response of n-damo to the slow increase of atmospheric CO2 concentration.
金靖昊,黄翯宸,沈李东,田茂辉,刘心,杨王挺,杨钰铃,刘佳琦,任冰洁,徐江兵,胡正华.稻田亚硝酸盐型甲烷厌氧氧化对大气CO2浓度缓增的响应[J].土壤学报,2023,60(6):1778-1789. DOI:10.11766/trxb202111250641 JIN Jinghao, HUANG Hechen, SHEN Lidong, TIAN Maohui, LIU Xin, YANG Wangting, YANG Yuling, LIU Jiaqi, REN Bingjie, XU Jiangbing, HU Zhenghua. Response of Nitrite-dependent Anaerobic Methane Oxidation in Paddy Fields to Slow Increase of Atmospheric CO2 Concentration[J]. Acta Pedologica Sinica,2023,60(6):1778-1789.复制